This study will recruit 40 YMSM and 40 Roma high-risk social networks. Each network will be randomly assigned to receive either standard HIV/AIDS risk reduction or the intervention. Networks assigned to receive the intervention will be assessed sociometrically to determine the 'social influence' leaders of each group. The leaders will then attend a 9-session program over the course of 3 months that will train them to deliver theory-based risk-reduction messages and peer-counseling to their respective social networks. The messages will focus on promoting safer sex knowledge, attitudes, intentions, perceived norms, and self-efficacy. All participants will be offered STD testing and their HIV-risk behavior will be assessed at Months 3 and 12. Participants assigned to receive the standard HIV/AIDS risk reduction will then receive the network intervention for an additional 12 months.